1. Field of the Invention
This invention generally relates to a powder collection device, and, in particular, to a device for collecting toner powder which is to used for developing an elastrostatic latent image and remaining on an image forming surface. More particularly, the present invention relates to a toner powder collection device for collecting toner powder from the surface of an image forming member such as a photosensitive member to be used in an electrophototgraphic copying machine and the like.
2. Description of the Prior Art
In electrostatography including electrostatic recording and electrophotographic copying technologies, various cleaning means have been used for removing the toner powder remaining on the surface of an image forming member, on which an electrostatic latent image is formed and developed by toner powder, after transfer of the deveoped image to a transfer medium such as paper. Although blade cleaners do have some disadvantages such that a surface to be cleaned and a blade to scrub the surface to be cleaned are easily worn out, they are presently widely used because of their stability and reliability in cleaning operation. In a blade cleaning system, the toner particles removed from the surface to be cleaned may be stuck between the cleaning blade and the surface or they may be deposited onto the blade thereby lowering the cleaning performance. In order to avoid such a disadvantage, various proposals have been made for collecting the toner particles removed from the surface to be cleaned by a blade.
FIG. 1 shows a prior art cleaning system using a cleaning blade for toner removal from an image forming surface. As shown, a cleaning blade 1 is disposed with its leading edge in scrubbing contact with the surface of a photosensitive drum 2, which is driven to rotate in the counterclockwise direction, at the location where the moving direction of the drum surface is pointed generally vertically upward. Thus the toner particles remaining on the drum surface are removed from the drum surface by the blade 1 and fall to the bottom of a casing 3. A toner powder transporting member 4 such as a rotating coil is disposed at the bottom of the casing 3 so that the toner powder is transported to a desired position by the transporting member 4. FIG. 2 shows another prior art cleaning system in which the photosensitive drum 2 is driven to rotate in the clockwise direction and a cleaning blade 5 is so disposed that its leading edge is in scrubbing contact with the surface of the drum 2 at the location where the moving direction of the drum surface is pointed generally vertically downward. Thus, the toner particles removed from the drum surface by the blade 5 slide down the top surface of the blade 5 and then they are collected into the casing 3. Similarly with the previous case, the rotating coil 4 is provided at the bottom of the casing 3 so that the collected toner particles may be transported to a desired location.
In a prior art toner powder collection system as described above, the toner particles may receive unacceptable mechanical stress thereby causing changes in mechanical properties; moreover, a cavity may be created in the toner powder collected in the casing 3 thereby causing no toner particles to be transported by the rotating coil 4.